泥页岩热演化过程中有机酸生成及其对致密油储层溶蚀作用的定量表征

Secondary pores of the tight sand reservoir (shale and tight sandstone) that corroded by organic acid is the main space of tight oil. Previous reviews on dissolution of tight reservoir are mainly concerned with tight sandstone, these lack the study of shale and are not associated with production of organic acids. The production of a certain amount of organic acid during thermal evolution can corrode minerals in shale such as feldspar, carbonate, etc. The extra organic acid expelled from shale can corrode the tight sand reservoir nearby the shale. In addtion, the study of production of organic acid mainly involves acid type, yield, factors and reaction mechanism, these studies haven't a numerical modelling so that acid yield and the corresponding dissolution pore of geologic periods can't be characterized quantitatively. Hydrous pyrolysis will be used to study production and decarboxylation of organic acid and dissolution of tight reservoir (shale and tight sandstone) during evolution of different organic matter types. This study focuses on defining factors and reaction mechanism of secondary pores of tight reservoir, especially shale reservoirs, building kinetic model of organic acid production and thermodynamic model of decarboxylation and corrosion of organic acid, and resurrecting produce process of secondary dissolution pores of tight reservoir, this will lay the foundation for forecasting sweet spots of tight oil exploration.

有机酸对致密油储层(泥页岩和致密砂岩)溶蚀所形成的次生孔隙是致密油的主要赋存空间。前人对致密储层溶蚀作用的研究主要针对致密砂岩，缺少对泥页岩的研究，而且没有与有机酸的生成相关联。实际上，泥页岩热演化过程中生成的有机酸首先会对其自身所含长石、碳酸盐等矿物产生溶蚀，之后"过剩"有机酸才会排出泥页岩溶蚀相邻致密砂岩。另外，目前对有机酸生成的研究主要涉及有机酸生成的种类、产率、影响因素和反应机理，缺少数值模拟研究，从而难以进行地质时期有机酸产率和相应的溶蚀孔隙发育的定量表征。本次研究计划通过加水热模拟实验，开展不同类型有机质热演化过程中有机酸生成、脱羧及有机酸对致密储层（泥页岩、致密砂岩）溶蚀的一体化研究；明确致密储层，特别是泥页岩储层溶蚀孔隙发育的机理和影响因素；建立有机酸生成的动力学及有机酸脱羧、溶蚀反应的热力学模型，再现不同地质时期致密储层溶蚀孔隙的发育过程，为致密油勘探甜点区预测奠定基础。

有机酸对致密油储层(泥页岩和致密砂岩)溶蚀所形成的次生孔隙是致密油的主要赋存空间。前人对致密储层溶蚀作用的研究主要针对致密砂岩，缺少对泥页岩的研究，而且没有与有机酸的生成相关联。实际上，泥页岩热演化过程中生成的有机酸首先会对其自身所含长石、碳酸盐等矿物产生溶蚀，之后"过剩"有机酸才会排出泥页岩溶蚀相邻致密砂岩。另外，目前对有机酸生成的研究主要涉及有机酸生成的种类、产率、影响因素和反应机理，缺少数值模拟研究，从而难以进行地质时期有机酸产率和相应的溶蚀孔隙发育的定量表征。本次研究通过加水热模拟实验，开展了不同类型有机质热演化过程中有机酸生成、脱羧及有机酸对致密储层（泥页岩、致密砂岩）溶蚀的一体化研究；明确致密储层，特别是泥页岩储层溶蚀孔隙发育的机理和影响因素；建立了有机酸生成的动力学及有机酸脱羧、溶蚀反应的热力学模型，再现了不同地质时期致密储层溶蚀孔隙的发育过程，为致密油勘探甜点区预测奠定了基础。